An operator may place three-dimensional media objects on the flatbed surface in order to print images on the media objects according to digital images which have been offered to the control unit.
The flatbed printer comprises a camera system connected to the control unit and positioned above the flatbed surface. The camera system comprises a camera above the flat bed surface at a predetermined height from the flat bed surface. The camera is calibrated to take pictures of the flat bed surface. Each location in a picture taken by the camera corresponds to a position in the plane of the flat bed surface. A non-linear calculation executed by image processing means in the control unit couples a pixel in the picture to a position of the flat bed surface. The image processing means is configured to analyse the picture of the flat bed surface in order to detect a media object placed on the flat bed surface. A contour of the media object may also be detected by the image processing means. By the contour of the media object is meant the contour that is visible from the camera point of view. Actual coordinates of points corresponding to points in the picture on the contour of the media object on the flat bed surface may be calculated by the control unit. Pair of points of the media object may be selected in order to store a distance between points of the pair. The stored distance may characterize a height of the media object, a width of the media object, a length of the media object or a diameter of the media object.
However, if the media object has a certain substantial height in the direction perpendicular to the flat bed surface, calculated coordinates of a point of the media object are not accurate and deviate from the real coordinates of the point. As a consequence, when ejecting marking material from the print head towards the media object, recording material may land beside the media object on the flat bed surface or an upper area of the media object along a part of the contour of the media object may be detrimentally unprinted. This will lead to pollution of the flatbed surface or to degradation of the print quality of the print on the media object.
It is an object of the present invention to achieve an increase of the print quality of a print on a media object if the media object has a substantial height in the direction perpendicular to the flat bed surface.